UDC 621.3.018.51
S. N. Kirillov, Dr. Sc. (Tech.), full professor, Head of the Department, RSREU, Ryazan, Russia;
orcid.org/0000-0002-3673-5709, e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
I. V. Lukashin, junior researcher, RSREU, Ryazan, Russia;
orcid.org/0000-0002-6136-4022, e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
OFDM technology is advisable to be used for implementation of high-speed communication systems adaptive to current signal-noise environment. High sensitivity to carrier frequency offset estimation errors is one of its drawbacks. The reduction of OFDM communication system sensitivity to the presence of carrier frequency offset is possible by reducing carrier frequency offset estimation variance. One solution to this problem is based on the processing of periodically transmitted preamble. The aim is to develop a procedure for adapting the preamble structure to reduce carrier frequency offset estimation variance in the operation of OFDM communication system in a frequency selective fading channel. A two-stage procedure of multicriteria synthesis based on a combined quality index is proposed to adapt a preamble structure. The quality index proposed allows controlling fractional and integer carrier frequency offset variance and symbol time offset. The use of synthesized preamble for fractional carrier frequency offset estimation is shown to provide reduction of a variance level up to 1,9 times in a non-stationary (maximum Doppler shift – 50Hz) frequency selective fading channel. The use of synthesized preamble for integer carrier frequency offset estimation provides reduction of the variance level up to 36,6 times.
Key words: OFDM, preamble, multicriterion optimization, adaptation, frequency-selective fading, synchronization algorithm, cognitive radio, non-coherent processing.